I reflashed the firmware an awful lot of times in order to solve that problem so I guess I have all the latest configs:

BIOS_VERSION = Aero-01.00.13

OS_VERSION = Poky Aero (Intel Aero linux distro) v1.6.1 (pyro)

AIRMAP_VERSION = 1.8

FPGA_VERSION = 0xc2

Aero FC Firmware Version = 3.5.3

When did you begin to notice this issue (out-of-box, after a firmware update, after a crash)?

We did not test it out-of-the-box, so I wouldn't be able to answer that one. When we received it, we went straight to a manual flight test, in which we DID notice the drone was tilted when flying and would not respond to neither RTL or pos hold. Nevertheless, we continued trying to calibrate it via controller trims and eventually crashed the drone.

Is there any way to test antenna integrity? I'm quite sure both connections and antenna position are ok.

Since the compass was calibrated it means the GPS should be connected. Please try to restart the GPS in the shell command line using these commands: gps stopgps startThen run the command "gps status" and please provide us with the output of this command.

Also, please check if other gps devices are able to obtain signal at your location.